It has the name "subway" because it was born underground in 1904. That's where the name came from and has stood as the name until now. The IRT subway was the first subway. By the time they unified the system the whole entire system became known as the subway.
Just remember, the Staten Island Railway is a railroad. It would be wrong to label it a subway. I wouldn't mind changing it to the SIRR (Staten Island Railroad). B)
You guys have quiet an impressive collection. Looking forward to seeing more pictures. I used to have old subway maps that I passed along to my nephews.
I thought the R44's of the SIR had at least 10 more years of service in them. It would be nice to see something different on the SIR even if its the hand me downs from the main subway network.